Wilford

Wilford's first aircraft, built in conjunction with Vincent Burnelli and entered for the Guggenheim Safe Airplane Contest in 1927, was especially designed for low-speed landing.
In 1928 Wilford visited Europe, and while there acquired the patent rights for the United States of a rotary wing aircraft conceived by a German named Rieseler. In 1929 Wilford began building his own gyroplanes.
The idea behind this American/German partnership was a scheme for feathering the pitch of the blades rotating round the hub instead of the blade flapping system which La Cierva employed in his autogyros.